Hadoop ,originally developed by yahoo based on a paper published on google file system, is primarily a distributed file system which provides fast access to the file and the data within. However, at present it refers to a whole set of software that help in taking the full advantage of the possibilities offered by Hadoop.
It includes frameworks like Pig and Hive, database implementations like HBase , management tools like Ambari and Zookeeper as well as several use case specific libraries and tools.
E-commerce, Security and Compliance requirements, ease of data collection, Social media and advent of Internet of Things has been the primary driver in exponential growth of data being collected by the organizations
Traditional systems for database and file systems have either failed to meet the requirements of scalability or have become prohibitively expensive to run and maintain at what is now called "Internet Scale" or Big Data. Hadoop provides proven solution to these problems. Its power and popularity can be be seen here